Sitecore in on a journey from monolith to NET Core based Service Architecture by leaving the safety of the monolith but because of tight coupling we have to live with large instances, slow start up and all or nothing upgrades. This old approach is hard to scale, bug in one feature can affect the whole platform. It always slowed down the adoption of new technologies. Now, Sitecore is going into direction where they creating a new building blocks on the same Sitecore Host (hOS+). One of them is Universal Tracker. But what is it ?
Universal Tracker is a headless API for xDB collection. You asking your self isn’t that xConnect? It is not. xConnect only accepts immutable history and it designed for trusted service communication – Authentication only, no authorization. Universal Tracker is needed to not expose xConnect. I has been told that in the future, Sitecore will use Universal Tracker instead of Sitecore.Analytics.Tracker. The Universal Tracker will allow collection of interaction data from all channels, wherever they may be, including Sitecore websites (web tracker), other websites (JS tracker) and even mobile applications (mobile tracker).
Where xConnect is concerned with collecting completed interactions, the universal tracker is concerned with collecting live interactions as they happen, and submit them to xConnect when they’re done.